Enthalpy of combustion of carbon to `CO_(2)` is `-393.5 kJ mol^(-1)`. Calculate the heat released upon formation of `35.2 g` of `CO_(2)` from carbon and dioxygen gas.

Options

A. `-315 KJ`
B. `+315KJ`
C. `-630 KJ`
D. `-3.15 KJ`

Answer

A

Explanation

Given, `C(s) + O_(2)(g) to CO_(2)(g)` ,
`Delta_(f)H=-393.5 KJ "mol"^(-1)`
Heat released on formation of 44 g or 1 mole
`CO_(2) =- 395.5 KJ "mol"^(-1)`
`because ` Heat released on formation of 35.2 g of `CO_(2)`
`=(-393.5 KJ "mol"^(-1))/(44 g) xx35.2 g =- 315 KJ "mol"^(-1)`